Midterm Study Guide

Exam Format

The format of the midterm exam will be closed book, closed notes. No calculators or electronic devices will be allowed. Only basic math skills are required for the exam. You will have as much paper as you need to complete the exam. CHEATERS ARE LOSERS, DON'T CHEAT!

The exam will consist of multiple choice, fill in the blank and short essay questions. The exam should take you no more than 1 1/2 hours to complete and that is how much time you have. If you are having an unreasonably difficult time with the exam, chances are others are as well. Do the questions you know the best first and come back to the hard ones later. There is a grading curve to correct any problems in the exam or my instruction that led up to the exam.

Topics Covered

The recommended reading material we have covered up to the point of the midterm can be used as one study guide. However, the hand-outs, class lectures and class notes are the definitive reference for the exam. I encourage you to pose questions in the HyperNews group about the sample questions or core concepts below. Typically I can respond the same day and with more detail and clarification than I have otherwise had the opportunity in class. Below is a list of concepts you should be prepared for on the exam.

  1. Introduction to Computer Networking

    1. Basic Definitions and Concepts

      1. Data Transmission

      2. Topologies

      3. Media

      4. LANs, MANs, and WANs

      5. Serial and Parallel

      6. Multiplexing

      7. Simplex, Half-duplex, and Full-duplex

      8. Connection-oriented and Connetionless

      9. Circuit Switching and Packet Switching

      10. Standards

      11. Protocols

      12. Layering

      13. Headers, Data and Trailers

      14. Encapsulation

    2. ISO OSI Reference Model

    3. TCP/IP Model

    4. End-to-end Argument
  2. Physical Layer

    1. Numbering Systems

    2. Analog and Digital

      1. Modulation

      2. Encoding

      3. Baseband and Broadband

    3. Undesirable Effects

    4. Sampling Theorem (Nyquist) and Shannon's Limit

    5. Timing

    6. Repeaters

    7. Hubs

    8. Throughput versus Bandwidth

  3. Datalink Layer

    1. Basic Concepts

      1. Interface

      2. LANs and topologies

      3. Shared media

    2. Ethernet

      1. CSMA/CD operation

      2. Back-off Algorithm

      3. Collisions
      4. Collision Domain

      5. Addressing

      6. Frame Fields

      7. Wiring

      8. High-speed Ethernet

    3. Token Ring

      1. Token ring operation

      2. FDDI operation

    4. Logical Link Control

  4. LAN Bridges and Switches

    1. Motivation and concepts

    2. Transparent Briding

      1. Address tables

    3. Bridging Dissimiliar LANs

    4. Spanning Tree

      1. Motiviation and concepts

      2. Forwarding and blocking

    5. Source Route Briding

    6. Bridge Filters

    7. LAN Switches

  5. Network Layer

    1. Motivation and key functions

    2. Internet Protocol

      1. Addressing

        1. Historic Class Addressing

        2. Dotted Decimal Notation

        3. Special Addresses

        4. Subnetting

        5. VLSM

        6. Supernetting

        7. CIDR

      2. Packet Fields

    3. Routing

      1. Basic concepts

      2. Routing tables

      3. Distance Vector

      4. Link State

    4. Address Resolution Protocol

    5. DHCP

  6. Transport Layer

    1. Motivation and key concepts

    2. Transmission Control Protocol

      1. Basic operation

      2. Retransmissions

      3. Timers

      4. Flow control

      5. Sliding Window

      6. Connection Startup/Shutdown

      7. Sequencing

      8. Application Multiplexing with Ports

      9. TCP Segment Fields

    3. User Datagram Protocol

Sample questions

  1. Convert the decimal number 5193 into its binary equivelant

  2. Compare and contrast the TCP/IP model with the OSI model of protocols.
  3. Imagine a LAN with 4 stations attached to it. Draw a picture of the LAN as a star wired topology, a bus wired topology and a ring wired topology (3 pictures total)
  4. Explain how TCP can operate in half-duplex mode
  5. Give an example of a packet switched, connection-oriented protocol.
  6. At what layer in the OSI model would UDP fit?
  7. What would be more important for a interactive session (e.g. TELNET), bandwidth or latency? Why?
  8. Explain in detail, how an Ethernet station arbitrates access to the LAN for frame transmission.
  9. Name at least 5 differences between a token ring LAN and a Ethernet LAN.
  10. Give an example of when LLC would be required.
  11. Why would you likely see LLC frames on an Ethernet network with transparent bridges?
  12. How would a bridge filter IP datagrams from being forwarded?
  13. When is multicast transmission used?
  14. Explain the difference between cut-through and store-and-forward switching
  15. How many bits in a standard IEEE 802 LAN based station address?
  16. If you had a router with 4 interfaces (4 IP networks) and a total IP address space of 140.192.5.0/22 to work with, how might you divide the address space equally among the subnet?
  17. What is the difference between subnetting and supernetting?
  18. Why has the original class hierarchy of IP addressing been abandoned?
  19. What will a router not do with an IP packet whose TTL field is set to zero?
  20. Explain the count-to-infinity problem and why distance vector routing protocols are susceptible to this problem.
  21. If you have a TCP connection open with a remote host and it suddenly sends a FIN for the connection, what should you do?
  22. What is the difference between an acknowledgement number and a sequence number in TCP?

For more sample questions, see last quarter's midterm study guide and last quarter's midterm exam [doc].

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Last updated: October 11, 2000